Dual thyroid ectopia-role of thyroid scintigraphy and neck ultrasonography

Ectopic thyroid tissue (ETT) is a rare developmental anomaly of the thyroid tissue where the thyroid gland is not located in its usual position. Dual thyroid ectopia is far rarer. This case of a 5-year-old euthyroid girl with thyroglossal cyst was planned for surgery. Presurgical ultrasonography (USG) of the neck followed by thyroid scintigraphy was performed. There was absent normal thyroid gland with single ETT in neck swelling on USG. However, thyroid scintigraphy revealed two ectopic foci of thyroid tissue; one was corresponding to neck swelling, and other was superior to it at the base of the tongue along with absent eutopic thyroid gland. The repeat neck USG could demonstrate the same. The present case emphasizes that, if the thyroid gland is not visible by USG; ETT should be evaluated with thyroid scintigraphy in case of thyroid dysgenesis.